The invention relates to bicycles including a multi-gear cassette or multi-sprocket cassette with different sized sprockets for engaging a chain, such as a roller chain. In particular, the invention relates to devices and methods for the damping of noise created by the interaction of a roller chain and a sprocket of a multi-gear cassette in a drive assembly of a bicycle.
In the case of bicycle drives, it has been shown that the un-damped percussion of the chain upon the run-in of the chain onto the sprocket leads to the following perturbations. When the impact of the percussion leads to high acceleration forces exerted on the end of the chain member running in, lubricants in this area separate from the chain member. In addition, when the chain roller contacts the sprocket, the radial play is eliminated between the chain roller and the collar on the roller link plate of the chain, but only on one side of the chain roller. As a result, the lubricant occupying this free volume is squeezed out forcefully. Also, the impacts occurring when the chain rollers contact the sprocket lead to vibrations which can in turn also lead to resonances in the slack span of chain. These resonances can be perceived by the operator, and can influence the system efficiency negatively. In addition, the percussion of the chain rollers on the sprocket teeth leads to the emission of noise. These noise emissions can be additionally amplified by light and stiff drive components. This is the case with multi-gear cassettes, for example, wherein individual sprockets are connected to each other to form a single part, and into a hollow, conical support body. The conical support body is designed with thin walls for the purpose of saving weight. An example of a conical support body is shown in EP 1 972 541. The support body is excited into oscillations and functions to a certain degree as a resonator which emits sound outward.